What does the cardiac cycle comprise of
- Pump cycle
- Opening and closing of valves
- Changes in aortic, ventricular and atrial pressure
- Changes in ventricular volume
What stages can the cardiac cycle be split into
- Mid-to-late diastole
- Systole
- Early diastole
Describe aortic pressure
- Used for blood pressure monitoring
- Minimum - diastolic
- Highest - systolic
- Dicrotic notch caused by shutting of aortic valve
Whats the definition of stroke volume
The volume of blood pumped by the LV in one contraction
Whats the definition of ventricular diastole
The phase of the heartbeat when ventricles fill with blood
Whats the definition of ventricular systole
The phase of the heartbeat when ventricles contract
Whats the definition of mean arterial pressure
The average aortic pressure during one cardiac cycle
Whats the definition of end diastolic volume
The volume of blood in a ventricle at the end of diastole
Whats the definition of isovolumetric contraction
When ventricles contract, but there’s not enough pressure to open semilunar valves, ventricular volume remains constant
Whats the definition of isovolumetric relaxation
when ventricles relax, but there’s too much pressure to open atrioventricular valves or keep semilunar valves open, all valves shut, no change in ventricular volume
What are the heart sounds
- First sound occurs at start of systole when the AV valves close
- Second sound occurs at start of diastole when the SL valves close
Describe coronary heart disease
- Caused by accumulation of atherosclerotic plaques in coronary arteries
- Plaques restrict blood flow to the myocardium - leads to chest pain
- Blockade of blood flow causes a heart attack
How is a PTCA carried out
- Balloon inflation induces ischaemia in the heart
- Damage to vessel may lead to reclosure in 3-6 months
- Restenosis prevented by introducing stents
- Acute treatment for myocardial infarction
Describe the coronary artery bypass graft
- Risk of complication
- Involves stopping the heart
- Grafts can still restenose
What are the 2 categories of congenital heart disease
- Acyanotic
- Cyanotic
Describe an acyanotic heart disease
- Blood to systemic circuit has normal level of oxygen carried
- Narrowing of the aorta
- Patent ductus arteriosus - Persistent opening between 2 main blood vessels leaving the heart, so blood re-enters heart and puts pressure on ventricles leading to hypertorphic cardiomyopathy
Describe a cyanotic heart disease
- Blood to systemic circuit has reduced oxygen carriage
- Very little blood reaches pulmonary circulation
- Ventricular septal defect – blood flows directly from left to right ventricle - caused by incomplete development of septum
